Following the Nationals' 1-0 victory over the Seattle Mariners on Thursday afternoon, Rizzo said that Riggleman quit after he requested the team pick up the option on his contract for 2012 and the club declined.

The team will name an interim manager Friday before the Nationals face the White Sox.

Washington is the parent club of the Triple-A Syracuse Chiefs.

Rizzo said Riggleman told him he would not travel with the team to Chicago. Riggleman was unavailable after the Nationals won for the 11th time in 12 games.

Riggleman is the second manager to resign this week. Florida Marlins manager Edwin Rodriguez quit Sunday.